Piezoelectric actuators are solid-state devices that may be utilized to convert an electric potential, or voltage, into mechanical motion. Piezoelectric actuators include a piezoelectric element having a first side and an opposed second side, a first metallic electrode deposited on the first side, and a second metallic electrode deposited on the second side. The metallic electrodes provide a mechanism by which the electric potential may be applied to the piezoelectric element, and the piezoelectric element deforms upon application of the electric potential.
When the piezoelectric element deforms, the metallic electrodes also deform, straining the metallic electrodes. This strain may cause the metallic electrodes to work-harden and/or to crack into domains, and the presence of these domains may cause different electrical potentials to be applied to different regions of the piezoelectric element upon application of the electric potential. The variation in electric potential among the domains also may cause electrical arcing among the domains, which may decrease an operational lifetime of the piezoelectric actuator.
Various solutions to the above-described issue have been proposed. As an example, the applied electric potential may be maintained below a threshold value, thereby limiting the strain within the metallic electrodes. As another example, a copper ring may be deposited on the metallic electrodes. While these solutions may be effective under certain circumstances, each has inherent limitations. Thus, there exists a need for improved actuator assemblies and methods of fabricating the same.